The present invention is method for detecting the presence and concentration of bone alkaline phosphatase (BAP) in human body fluids. Elevated BAP levels in serum is symptomatic for serious disorders such as bone metastasis from carcinomas such as those of the breast and prostate, and Paget's disease (osteitis deformous).
Paget's disease is a serious disease affecting primarily those over the age of 40. The disease is slowly progressive, first involving bone resorption followed by a distorted pattern of new growth in bones such as the pelvis, femur, skull, tibia, vertebrae, clavicle and humerus. The disease exhibits gross symptoms such as bowing of the tibia or femur, enlargement of the skull, shortened stature, and severe aching in the affected bones. Neural effects may include deafness or spinal cord compression accompanied by paresis or paraplegia.
Until now the only reliable diagnosis for Paget's disease has been by x-ray examination. Routine assays for serum BAP are confined to measuring total alkaline phosphatase concentration. Several related forms of alkaline phosphatase exist in the serum, specifically those of the intestinal, placental and the hepatic/renal/skeletal groups. These three broad groups can usually be separated using the time-consuming procedure of electrophoretic assay, but until now assays for distinguishing between the clinically important markers of bone and liver alkaline phosphatases (LAP) were at best ambiguous and time-consuming. The present invention is directed to a convenient highly specific sandwich immunoassay method for determining the presence or concentration of BAP and especially so in the presence of LAP.